Groundwater, Surface-Water, and Water-Chemistry Data, Black Mesa Area, Northeastern Arizona-2016-2018
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Prepared in cooperation with the Navajo Nation and Peabody Western Coal Company Groundwater, Surface-Water, and Water-Chemistry Data, Black Mesa Area, Northeastern Arizona—2016–2018 Open-File Report 2021–1124 U.S. Department of the Interior U.S. Geological Survey
A
B
C
D
Cover. A, Unnamed Spring near Dennehotso, Arizona B, hydrologic technician collecting water-level
measurement from a windmill powered stock well, C, base-flow discharge measurement using a Parshall flume
at Dinnebito Wash near Sand Springs, Arizona streamflow gaging station, D, municipal well and storage tank at
Kits’illi, Arizona. Photographs by Jon Mason, U.S. Geological Survey.
Groundwater, Surface-Water, and Water-Chemistry Data, Black Mesa Area, Northeastern Arizona—2016–2018 By Jon P. Mason Prepared in cooperation with the Navajo Nation and Peabody Western Coal Company Open-File Report 2021–1124 U.S. Department of the Interior U.S. Geological Survey
U.S. Geological Survey, Reston, Virginia: 2021 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Mason, J.P., 2021, Groundwater, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona—2016–2018: U.S. Geological Survey Open-File Report 2021–1124, 50 p., https://doi.org/10.3133/ ofr20201124. ISSN 2331-1258 (online)
iii
Contents
Abstract............................................................................................................................................................1
Introduction.....................................................................................................................................................1
Purpose and Scope...............................................................................................................................6
Previous Investigations........................................................................................................................7
Description of Study Area.............................................................................................................................9
Physiography..........................................................................................................................................9
Climate.....................................................................................................................................................9
Geology..................................................................................................................................................11
Geologic Units Below the N Aquifer........................................................................................11
Geologic Units of the N Aquifer................................................................................................11
Moenave Formation..........................................................................................................11
Wingate Sandstone...........................................................................................................12
Kayenta Formation.............................................................................................................12
Navajo Sandstone.............................................................................................................12
Carmel Formation...............................................................................................................13
Geologic Units of the D Aquifer................................................................................................13
Entrada Sandstone............................................................................................................13
Morrison Formation...........................................................................................................13
Dakota Sandstone.............................................................................................................13
Mancos Shale....................................................................................................................14
Geologic Units of the T Aquifer................................................................................................14
Mesaverde Group..............................................................................................................14
Bidahochi Formation.........................................................................................................14
Hydrologic Data............................................................................................................................................14
Withdrawals from the N Aquifer.......................................................................................................15
Withdrawals in Calendar Years 2017 and 2018 Compared to Previous Years...................17
Groundwater Levels in the N Aquifer...............................................................................................17
Spring Discharge from the N Aquifer...............................................................................................26
Surface-Water Discharge, Calendar Years 2017–18......................................................................31
Moenkopi Wash..........................................................................................................................31
Dinnebito Wash...........................................................................................................................31
Polacca Wash.............................................................................................................................32
Pasture Canyon Springs............................................................................................................33
Surface-Water Base Flow.........................................................................................................33
Water Chemistry..................................................................................................................................33
Water-Chemistry Data for Wells Completed in the N Aquifer.............................................36
Water-Chemistry Data for Springs that Discharge from the N Aquifer.............................36
Water-Chemistry Data for Streams that Receive Flow from the N Aquifer......................36
Summary........................................................................................................................................................41
References Cited..........................................................................................................................................46
iv
Figures
1. Map showing location of study area, Black Mesa area, northeastern Arizona.................3
2. Stratigraphic section showing rock formations and hydrogeologic units of the
Black Mesa area, northeastern Arizona....................................................................................5
3. Aerial photograph of Organ Rock monocline and folding strata of Skeleton Mesa
near Kayenta, Arizona...................................................................................................................9
4. Map showing mean annual precipitation, 1981-2010, Black Mesa area, Arizona............10
5. Aerial photograph of Moenave Formation outcropping on Garces Mesas,
northeastern Arizona..................................................................................................................12
6. Annual withdrawals from the N aquifer, Black Mesa area, northeastern Arizona,
1965–2018......................................................................................................................................17
7. Locations of well systems monitored for annual withdrawals from the N aquifer..........18
8. Map showing water-level changes in N-aquifer wells from the prestress
period to 2018...............................................................................................................................19
9. Plots of observed water levels (1950–2018) in annual observation-well network,
N aquifer........................................................................................................................................23
10. Plots of observed groundwater water-levels in continuous-record observation
wells BM1–BM6 from 1963 to 2018 in the N aquifer..............................................................27
11. Map of surface-water and water-chemistry data-collection sites, N aquifer..................28
12. Plots of discharge from, Moenkopi School Spring, Burro Spring, Pasture Canyon
Spring and Unnamed Spring near Dennehotso, N Aquifer...................................................29
13. Plots of daily mean discharge, calendar years 2017–2018 for Moenkopi Wash at
Moenkopi, Dinnebito Wash near Sand Springs, Polacca Wash near Second Mesa,
and Pasture Canyon Springs, Black Mesa area, northeastern Arizona.............................32
14. Plots of median winter flow for November, December, January, and February for
water years 1977–2017 for Moenkopi Wash at Moenkopi, Dinnebito Wash near
Sand Springs, Polacca Wash near Second Mesa and Pasture Canyon Springs,
Black Mesa area, northeastern Arizona..................................................................................34
15. Map showing water chemistry and distribution of dissolved solids in the N aquifer,
Black Mesa area..........................................................................................................................37
16. Plots of dissolved-solids concentrations for water samples from selected wells,
N aquifer, Black Mesa area.......................................................................................................38
17. Plots of concentrations of dissolved solids, chloride, and sulfate for water samples
from Moenkopi School Spring, Pasture Canyon Spring, Burro Spring, and Unnamed
Spring near Dennehotso, which discharge from the N aquifer in Black Mesa area,
northeastern Arizona..................................................................................................................43v
Tables
1. Withdrawals from the N aquifer, Black Mesa area, northeastern Arizona,
1965–2018........................................................................................................................................4
2. Tabulated list of progress reports for the Black Mesa monitoring program
1978–2018........................................................................................................................................7
3. Identification numbers and names of monitoring program study wells, 2017–18,
Black Mesa area, northeastern Arizona..................................................................................15
4. Withdrawals from the N aquifer by well system, Black Mesa area, northeastern
Arizona, calendar years 2017 and 2018....................................................................................16
5. Total, industrial, and municipal withdrawals from the N aquifer for discrete time
periods from 1965 to 2018, Black Mesa area, northeastern Arizona..................................17
6. Water-levels measured in monitoring program wells completed in the N aquifer
during calendar years 2017 and 2018, and water level changes from the prestress
period to calendar year 2018, Black Mesa area, northeastern Arizona.............................20
7. Well-construction characteristics, depth to top of N aquifer, and 2018 static water
level for wells used in annual water-level measurements and for continuous-record
observation wells, 2017–18, Black Mesa area, northeastern Arizona................................21
8. Median changes in water levels in monitoring-program wells from prestress
period to 2018, N aquifer, Black Mesa area, northeastern Arizona....................................22
9. Discharge from Moenkopi School Spring, Burro Spring, Pasture Canyon Spring,
and Unnamed Spring near Dennehotso, N Aquifer, Black Mesa area, northeastern
Arizona, 1952–2018......................................................................................................................30
10. Streamflow-gaging stations used in the Black Mesa monitoring program, their
periods of record, and drainage areas....................................................................................32
11. Comparison of chemical analyses of replicate and environmental water samples
taken from Burro Spring, Black Mesa area, northeastern Arizona, 2017..........................35
12. Chemical analyses of a field blank water sample processed at Unnamed Spring
near Dennehotso, Black Mesa area, northeastern Arizona, 2018.......................................35
13. Physical properties and chemical analyses of water samples from selected industrial
and municipal wells completed in the N aquifer, Black Mesa area, northeastern
Arizona, 2017.................................................................................................................................38
14. Specific conductance and concentrations of selected chemical constituents in
water samples from selected industrial and municipal wells completed in the N
aquifer, Black Mesa area, northeastern Arizona, during 1967–2017..................................39
15. Physical properties and chemical analyses of water samples from four springs in
the Black Mesa area, northeastern Arizona, in 2017–2018..................................................40
16. Specific conductance and concentrations of selected chemical constituents in
N aquifer water samples from four springs in the Black Mesa area, northeastern
Arizona, 1948–2018......................................................................................................................41
17. Physical properties and chemical analyses of water samples from selected
surface-water sites, Black Mesa area, northeastern Arizona, 2017..................................44
18. Total dissolved-solids concentrations at base flow from three stream in the Black
Mesa area, northeastern Arizona, 1976–2017.........................................................................45vi
Conversion Factors
U.S. customary units to International System of Units
Multiply By To obtain
Length
inch (in.) 2.54 centimeter (cm)
inch (in.) 25.4 millimeter (mm)
foot (ft) 0.3048 meter (m)
mile (mi) 1.609 kilometer (km)
Area
square mile (mi2) 2.590 square kilometer (km2)
Volume
acre-foot (acre-ft) 0.001233 cubic hectometer (hm3)
Flow rate
cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)
gallon per minute (gal/min) 0.06309 liter per second (L/s)
gallon per year 3.785 liter per year (L/yr)
Datum
Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929
(NGVD 29).
Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).
Altitude, as used in this report, refers to distance above the vertical datum.
Supplemental Information
Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at
25 °C).
Concentrations of chemical constituents in water are given in either milligrams per liter (mg/L)
or micrograms per liter (µg/L).vii Abbreviations ADWR Arizona Department of Water Resources BIA Bureau of Indian Affairs C aquifer Coconino aquifer D aquifer Dakota aquifer EPA U.S. Environmental Protection Agency MCL Maximum Contaminate Level N aquifer Navajo aquifer NTUA Navajo Tribal Utility Authority NWIS National Water Information System NWQL National Water Quality Laboratory PWCC Peabody Western Coal Company QC Quality control SMCL Secondary Maximum Contaminate Level T aquifer Toreva aquifer USGS United States Geological Survey
Groundwater, Surface-Water, and Water-Chemistry Data,
Black Mesa Area, Northeastern Arizona—2016–2018
By Jon P. Mason
Abstract and Unnamed Spring near Dennehotso. Discharge at Burro
Spring has remained relatively constant since it was first mea-
The Navajo (N) aquifer is the primary source of ground- sured in the 1980s and discharge at Pasture Canyon Spring has
water in the 5,400-square-mile Black Mesa area in northeast- fluctuated for the period of record.
ern Arizona. Availability of water is an important issue in the Continuous records of surface-water discharge in the
Black Mesa area because of continued water requirements Black Mesa area were collected from streamflow-gaging
for industrial and municipal use by a growing population and stations at the following sites: Moenkopi Wash at Moen-
because of its arid climate. Precipitation in the area typi- kopi 09401260 (1976 to 2018), Dinnebito Wash near Sand
cally ranges from less than 6 to more than 16 inches per year Springs 09401110 (1993 to 2018), Polacca Wash near Second
depending on location. Mesa 09400568 (1994 to 2018), and Pasture Canyon Springs
The U.S. Geological Survey water-monitoring program in 09401265 (2004 to 2018). Median winter flows (November
the Black Mesa area began in 1971 and provides information through February) of each water year were used as an index
about the long-term effects of groundwater withdrawals from of the amount of groundwater discharge at the above-named
the N aquifer for industrial and municipal uses. This report sites. For the period of record, the median winter flows have
presents results of data collected as part of the monitoring pro- generally remained constant at Dinnebito Wash and Polacca
gram in the Black Mesa area from November 2016 to Decem- Wash, whereas a decreasing trend was indicated at Moenkopi
ber 2018. The monitoring program includes measurements Wash and Pasture Canyon Springs.
of (1) groundwater withdrawals (pumping), (2) groundwater In 2017 and 2018, water samples collected from two
levels, (3) spring discharge, (4) surface-water discharge, and wells, four springs, and three streams in the Black Mesa area
(5) groundwater and surface-water chemistry. were analyzed for selected chemical constituents. The results
In calendar year 2017, total groundwater withdrawals from wells and springs were compared with previous analyses
were 3,710 acre-feet (acre-ft), industrial withdrawals were from the same wells and springs. At the Peabody 2 well, a
1,110 acre-ft, and municipal withdrawals were 2,600 acre-ft. significant (p0.05) at the Kykotsmovi PM2
municipal withdrawals were 2,500 acre-ft. Total withdrawals well. Dissolved solids, chloride, and sulfate concentrations
during 2017 and 2018 were about 49 percent less than total increased at Moenkopi School Spring during the more than
withdrawals in 2005 because of Peabody Western Coal Com- 30 years of record at that site. Concentrations of dissolved
pany’s discontinued use of water to transport coal in a coal solids, chloride, and sulfate at Pasture Canyon Spring have not
slurry pipeline. varied significantly (p>0.05) since the early 1980s, and there is
From the prestress period (prior to 1965) to 2018, mea- no increasing or decreasing trend in those data. Concentrations
sured water levels available for comparison in wells completed of dissolved solids, chloride, and sulfate at Burro Spring and
in the unconfined areas of the N aquifer within the Black Mesa Unnamed Spring near Dennehotso have varied for the period
area declined in 8 of 14 wells, the changes ranged from +12.1 of record, but there is no statistical trend in the data. Baseflow
feet to −39.4 feet, and the median change was -0.6 feet. Water water chemistry samples were collected from Moenkopi,
levels also declined in 15 of 18 wells measured in the confined Dinnebito, and Polacca washes in 2017. Samples from all
area of the aquifer. The median change for the confined area three washes had total-dissolved solids concentrations higher
of the aquifer was −40.2 feet (ft), with changes ranging from than is typically found in the N aquifer water.
+14.2 ft to −189.0 ft. From the prestress period to 2018, the
median water-level change for all 32 wells in both the con-
fined and unconfined areas was −9.4 ft.
Introduction
Spring flow was measured at four springs in 2017 and The 5,400-square-mile (mi2) Black Mesa study area is
2018. Flow fluctuated during the period of record for Burro enclosed within the Navajo and Hopi Indian Reservations in
Spring and Pasture Canyon Spring, but a decreasing trend was northeastern Arizona (fig. 1). It contains diverse topography
statistically significant (p2 Groundwater, Surface-Water, and Water-Chemistry Data, Black Mesa Area, Northeastern Arizona—2016–2018 Introduction 3
111°30' 111°00’ 110°30' UTAH 110°00’ 109°30'
37°00’ ARIZONA
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COCONINO COUNTY
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Figure 1. Map showing location of study area, Black Mesa area, northeastern Arizona. Boundary
Pue
35°30' of study area is based on boundary of groundwater model from Eychaner, 1983.
Base from U.S. Geological Survey digital data, 2010 0 5 10 15 20 25 MILES Modified from Brown and Eychaner, 1988
Lambert Conformal Conic projection
Standard parallels 29°30’ N. and 45°30’ N., 0 5 10 15 20 25 KILOMETERS
central meridian -111°30’ W.4 Groundwater, Surface-Water, and Water-Chemistry Data, Black Mesa Area, Northeastern Arizona—2016–2018
Black Mesa, a topographic high at the center of the study area, northeastern part of the study area where it would be deeply
encompasses about 2,000 mi2. It has 2,000-foot-high cliffs buried. The N aquifer is confined under most of Black Mesa,
on its northern and northeastern sides, but it slopes gradually and the overlying stratigraphy limits recharge to this part of
down to the south and southwest. Availability of water is the aquifer. The N aquifer is unconfined in areas surround-
an important issue in the study area because of continued ing Black Mesa, and most recharge occurs where the Navajo
groundwater withdrawals, the growing population, and an arid Sandstone is exposed in the area near Shonto (fig. 1) (Lopes
to semiarid climate. and Hoffmann, 1997). From the recharge areas near Shonto,
Aquifers that are utilized in the Black Mesa area include groundwater moves radially southwest toward Tuba City,
the Toreva (T), Dakota (D), and Navajo (N) aquifers (fig. 2). south toward the Hopi Reservation, and east toward Rough
Shallow aquifers composed of surficial sediments or volca- Rock and Dennehotso (Eychaner, 1983).
nic rock are used locally to supply small quantities of water. Within the Black Mesa study area, the Navajo Nation
The N aquifer is the major source of water for industrial and Hopi Tribe are the principal municipal water users, and
and municipal uses in the Black Mesa area. For this reason, PWCC is the principal industrial water user. Withdrawals from
groundwater data collected for this report was exclusively the N aquifer in the Black Mesa area increased fairly consis-
from the N aquifer. Water from the T and D aquifers are not tently from 1965 through 2005 and then decreased markedly
used in substantial quantities in the Black Mesa area. Water in 2006 (table 1). PWCC began operating a strip mine in the
from the T aquifer is used locally for livestock watering and northern part of the study area in 1968 (highlighted red in
to irrigate small plots of land, but it likely cannot produce fig. 1). PWCC’s mining operation consisted of two mines on
enough water for municipal or industrial use. Water from the Black Mesa—the Kayenta mine, which transported coal to the
D aquifer is used locally for livestock watering and has con- Navajo Generating Station by train, and the Black Mesa mine,
tributed to some wells at the Peabody Western Coal Company which transported coal 275 miles to the Mohave Generating
(PWCC) well field, but water from the aquifer has elevated Station by a water-based coal slurry pipeline.
total-dissolved solids concentrations that make it unsuitable PWCC operated both mines on Black Mesa from the
for municipal use. The deeper Coconino (C) aquifer is present 1970s until about 2005, when the Mohave Generating Station
throughout the Black Mesa area, but it is deeply buried and ceased operations. On December 31, 2005, PWCC reduced
likely has total-dissolved solids concentrations above what can pumping of the N aquifer by approximately 70 percent as
be used without treatment. a result of discontinued use of the coal slurry pipeline that
According to Eychaner (1983) the N aquifer is composed delivered water, in addition to coal, to the Mohave Generating
of three hydraulically connected formations—the Navajo Station. The two mines at PWCC have since been combined
Sandstone, Kayenta Formation, and Wingate Sandstone—that into the Black Mesa Complex, which still delivers coal to the
function as a single aquifer (fig. 2). However, more recent Navajo Generating Station by an electric train. PWCC contin-
geologic mapping indicates the Wingate Sandstone is absent ued to pump about 1,100 to 1,600 acre-feet (acre-ft) per year
from much of the Black Mesa area. Outcrops of sandstone after 2005, primarily for dust control (table 1).
previously mapped as Wingate Sandstone in the Black Mesa There are four major stream systems that provide surface
area are now considered to be part of the Moenave Formation drainage for the Black Mesa area. They are Moenkopi Wash,
(Billingsley and others, 2012, 2013). Based on this recent geo- Dinnebito Wash, Oraibi Wash, and Polacca Wash. All four
logic mapping it is unclear if the Wingate Sandstone is present stream systems have headwaters high on Black Mesa and
at all in the Black Mesa area. If present it would only be in the eventually drain into the Little Colorado River to the south
Table 1. Withdrawals from the N aquifer, Black Mesa area, northeastern Arizona, 1965–2018.
Industriala Municipalb,c Industriala Municipalb,c
Calendar Total Calendar Total
Year withdrawals Year withdrawals
Confined Unconfined Confined Unconfined
1965 0 50 20 70 1975 3,500 600 510 4,610
1966 0 110 30 140 1976 4,180 690 640 5,510
1967 0 120 50 170 1977 4,090 750 730 5,570
1968 100 150 100 350 1978 3,000 830 930 4,760
1969 40 200 100 340 1979 3,500 860 930 5,290
1970 740 280 150 1,170 1980 3,540 910 880 5,330
1971 1,900 340 150 2,390 1981 4,010 960 1,000 5,970
1972 3,680 370 250 4,300 1982 4,740 870 960 6,570
1973 3,520 530 300 4,350 1983 4,460 1,360 1,280 7,100
1974 3,830 580 360 4,770 1984 4,170 1,070 1,400 6,640Introduction 5
Water bearing in places
QUATERNARY
Volcanic rock ►
TERTIARY
Bidahochi
TERTIARY
Volcanic rock ►
Formation
and
Yale Point Sandstone
Mesa Wepo Formation EXPLANATION
Verde T aquifer Water bearing
Group
CRETACEOUS
Toreva Sandstone
Mancos Shale
Dakota Sandstone
Morrison
Formation
D aquifer
San Rafael Entrada Sandstone
Group
JURASSIC
Carmel Formation
Navajo Sandstone
Glen
Canyon N aquifer
Group
Kayenta Formation
Moenave Wingate
Formation Sandstone? ???1 ?1
Chinle Formation
TRIASSIC
Shinarump Member
Moenkopi Formation
Kaibab Limestone
Coconino Sandstone C Aquifer
PERMIAN
Supai Formation or Group
1
Unclear if present, some outcrops formerly mapped as Wingate Sandstone are now Modified from Harshberger and others, 1966
considered part of Moenave Formation (Billingsley and others, 2012, 2013).
Figure 2. Stratigraphic section showing rock formations and hydrogeologic units of the Black Mesa area,
northeastern Arizona (not to scale). The N aquifer is approximately 1,000 feet thick.
men20-2166_fig026 Groundwater, Surface-Water, and Water-Chemistry Data, Black Mesa Area, Northeastern Arizona—2016–2018
Table 1.—Continued
Industriala Municipalb,c Industriala Municipalb,c
Calendar Total Calendar Total
Year withdrawals Year withdrawals
Confined Unconfined Confined Unconfined
1985 2,520 1,040 1,160 4,720 2002 4,640 1,500 1,860 8,000
1986 4,480 970 1,260 6,710 2003 4,450 1,350 1,440 7,240
1987 3,830 1,130 1,280 6,240 2004 4,370 1,240 1,600 7,210
1988 4,090 1,250 1,310 6,650 2005 4,480 1,280 1,570 7,330
1989 3,450 1,070 1,400 5,920 2006 1,200 d
1,300 d
1,600 d
4,100
1990 3,430 1,170 1,210 5,810 2007 1,170 1,460 1,640 4,270
1991 4,020 1,140 1,300 6,460 2008 1,210 e,f
1,430 e
1,560 f
4,200
1992 3,820 1,180 1,410 6,410 2009 1,390 1,440 1,400 4,230
1993 3,700 1,250 1,570 6,520 2010 1,170 d
1,450 1,420 d
4,040
1994 4,080 1,210 1,600 6,890 2011 1,390 d
1,460 1,630 d
4,480
1995 4,340 1,220 1,510 7,070 2012 1,370 d
1,380 1,260 d
4,010
1996 4,010 1,380 1,650 7,040 2013 1,460 d
1,410 d
1,110 d
3,980
1997 4,130 1,380 1,580 7,090 2014 1,580 d
1,280 d
1,310 d
4,170
1998 4,030 1,440 1,590 7,060 2015 1,340 d
1,370 d
1,260 d
3,970
1999 4,210 1,420 1,480 7,110 2016 1,090 d
1,380 d
1,070 d
3,540
2000 4,490 1,610 1,640 7,740 2017 1,110 1,330 d
1,270 d
3,710
2001 4,530 1,490 1,660 7,680 2018 1,170 d
1,370 1,130 d
3,670
Metered pumpage from the confined part of the aquifer by Peabody
a
Geological Survey, 1980–85; and metered pumpage furnished by the Navajo
Western Coal Company. Tribal Utility Authority, the Bureau of Indian Affairs, various Hopi Village
Administrations, and the U.S. Geological Survey, 1986–2018.
b
Does not include withdrawals from the wells equipped with windmills.
d
Meter data were incomplete; therefore, municipal withdrawals are
c
Includes estimated pumpage 1965–73 and metered pumpage 1974–79
estmated, and total withdrawal uses an estimation in the calculation.
at Tuba City; metered pumpage at Kayenta and estimated pumpage at
Chilchinbito, Rough Rock, Piñon, Keams Canyon, and Kykotsmovi before e
Confined and unconfined totals were reversed in previous reports.
1980; metered and estimated pumpage furnished by the Navajo Tribal Utility f
Confined withdrawals are about 90 acre-ft greater than previously reported.
Authority and the Bureau of Indian Affairs and collected by the U.S.
Geological Survey, 1980–85; and metered pumpage furnished by the Navajo
Tribal Utility Authority, the Bureau of Indian Affairs, various Hopi Village
Administrations, and the U.S. Geological Survey, 1986–2011.
and southwest of the study area (fig. 1). Most reaches of these Purpose and Scope
streams are ephemeral, flowing only in response to runoff from
precipitation events, but a few short reaches flow at least part This report presents results of groundwater, surface-
of each year as a result of groundwater discharge. water, and water-chemistry monitoring in the Black Mesa
The members of the Navajo Nation and the Hopi Tribe area from November 2016 to December 2018. Continuous
have been concerned about the long-term effects of withdraw- and periodic groundwater and surface-water data are collected
als from the N aquifer on available groundwater supplies, on to monitor the possible effects of industrial and municipal
stream and spring discharge, and on groundwater chemistry. withdrawals from the N aquifer on groundwater levels, stream
In 1971, these water-supply concerns led to the establishment and spring discharge, and groundwater chemistry. Groundwa-
of a monitoring program for the water resources in the Black ter data include groundwater withdrawals (pumping), water
Mesa area by the U.S. Geological Survey (USGS) in coop- levels, spring-discharge rates, and water chemistry. Surface-
eration with the Arizona Water Commission, which was the water data include discharge rates at four continuous-record
predecessor to the present Arizona Department of Water streamflow-gaging stations and water chemistry from three
Resources (ADWR). In 1983, the Bureau of Indian Affairs of the gaging stations. Together, these data are compared
(BIA) joined the cooperative effort. Since 1983, the Navajo with groundwater and surface-water data from 1965 to 2018
Tribal Utility Authority (NTUA), the PWCC, the Hopi Tribe, to describe the overall status of and change over time of
and the Western Navajo, Chinle, and Hopi Agencies of the groundwater conditions in the N aquifer, as well as to pro-
BIA have assisted in the collection of hydrologic data. vide information on how the aquifer responds to groundwaterIntroduction 7
development stresses. Some statistical analyses of the data Stream-discharge and periodic water-quality data
are included in this report to examine trends in the data that collected from Moenkopi Wash before the 1982 water year
characterize groundwater conditions in the N aquifer. were published by the USGS (1963–64a,b; 1965–74a,b; and
1976–83). Stream-discharge data from water years 1983 to
Previous Investigations 2005 for Moenkopi Wash at Moenkopi (09401260), Dinnebito
Wash near Sand Springs (09401110), Polacca Wash near
Progress reports on the Black Mesa area monitoring Second Mesa (09400568), Laguna Creek at Dennehotso
program have been prepared by the USGS since 1978, and (09379180), and Pasture Canyon Spring (09401265) in the
these progress reports are summarized in table 2. The Black Mesa area were published in White and Garrett (1984,
groundwater-level, surface-water discharge, and water 1986, 1987, 1988), Wilson and Garrett (1988, 1989), Boner
chemistry data from the Black Mesa area monitoring program and others (1989, 1990, 1991, 1992), Smith and others (1993,
are contained in these progress reports and in the USGS 1994, 1995, 1996, 1997), Tadayon and others (1998, 1999,
National Water Information System (NWIS) database (http:// 2000, 2001), McCormack and others (2002, 2003), Fisk
waterdata.usgs.gov/az/nwis/). Water-withdrawal data are and others (2004, 2005, 2006), and online for year 2006 to
presented in tables in the progress reports. present (http://wdr.water.usgs.gov). Before the monitoring
Table 2. Tabulated list of progress reports for the Black Mesa monitoring program 1978–2018.
Year published Author(s) Title USGS report type and number
Progress report on Black Mesa monitoring
1978 U.S. Geological Survey Open-File Report 78–459
program—1977
Progress report on Black Mesa monitoring
1985 Hill, G.W. Open-File Report 85-483
program—1984
Progress report on Black Mesa monitoring
1986 Hill, G.W., and Whetten, M.I. Open-File Report 86-414
program—1985–86
Progress report on the ground-water, surface-water,
1987 Hill, G.W., and Sottilare, J.P. and quality-of-water monitoring program, Black Open-File Report 87–458
Mesa area, northeastern Arizona—1987
Progress report on the ground-water, surface-water,
1988 Hart, R.J., and Sottilare, J.P. and quality-of-water monitoring program, Black Open-File Report 88–467
Mesa area, northeastern Arizona—1987–88
Progress report on the ground-water, surface-water,
1989 Hart, R.J., and Sottilare, J.P. and quality-of-water monitoring program, Black Open-File Report 89–383
Mesa area, northeastern Arizona—1988–89
Results of ground-water, surface-water, and water-
Water-Resources Investigations
1992 Sottilare, J.P. quality monitoring, Black Mesa area, northeastern
Report 92–4008
Arizona—1989–90
Results of ground-water, surface-water, and water-
Water-Resources Investigations
1992 Littin, G.R. quality monitoring, Black Mesa area, northeastern
Report 92–4045
Arizona—1990–91
Results of ground-water, surface-water, and water-
Water-Resources Investigations
1993 Littin, G.R. quality monitoring, Black Mesa area, northeastern
Report 93–4111
Arizona—1991–92
Results of ground-water, surface-water, and water-
Water-Resources Investigations
1995 Littin, G.R., and Monroe, S.A. quality monitoring, Black Mesa area, northeastern
Report 95–4156
Arizona—1992–93
Results of ground-water, surface-water, and water-
Water-Resources Investigations
1995 Littin, G.R., and Monroe, S.A. chemistry monitoring, Black Mesa area, northeast-
Report 95–4238
ern Arizona—1994
Ground-water, surface-water, and water-chemistry
1996 Littin, G.R., and Monroe, S.A. Open-File Report 96–616
data, Black Mesa area, northeastern Arizona—1995
Ground-water, surface-water, and water-chemistry
1997 Littin, G.R., and Monroe, S.A. Open-File Report 97–566
data, Black Mesa area, northeastern Arizona—19968 Groundwater, Surface-Water, and Water-Chemistry Data, Black Mesa Area, Northeastern Arizona—2016–2018
Table 2.—Continued
Year published Author(s) Title USGS report type and number
Littin, G.R., Baum, B.M., and Ground-water, surface-water, and water-chemistry
1999 Open-File Report 98–653
Truini, Margot data, Black Mesa area, northeastern Arizona—1997
Truini, Margot, Baum, B.M.,
Ground-water, surface-water, and water-chemistry
2000 Littin, G.R., and Shingoite- Open-File Report 00–66
data, Black Mesa area, northeastern Arizona—1998
wa-Honanie, Gayl
Thomas, B.E., and Truini, Ground-water, surface-water, and water-chemistry
2000 Open-File Report 00–453
Margot data, Black Mesa area, northeastern Arizona–1999
Ground-water, surface-water, and water-chemistry
data, Black Mesa area, northeastern Arizo- Water-Resources Investigations
2002a Thomas, B.E.
na—2000–2001, and performance and sensitivity of Report 02–4211
the 1988 USGS numerical model of the N aquifer
Ground-water, surface-water, and water-chemistry
2002b Thomas, B.E. data, Black Mesa area, northeastern Arizo- Open-File Report 02–485
na—2001–02
Ground-water, surface-water, and water-chemistry
Truini, Margot, and Thomas,
2004 data, Black Mesa area, northeastern Arizo- Open-File Report 03–503
B.E.
na—2002–03
Ground-water, surface-water, and water-chemistry
Truini, Margot, Macy, J.P., and
2005 data, Black Mesa area, northeastern Arizo- Open-File Report 2005–1080
Porter, T.J.
na—2003–04
Ground-water, surface-water, and water-chemistry
2006 Truini, Margot, and Macy, J.P. data, Black Mesa area, northeastern Arizo- Open-File Report 2006–1058
na—2004–05
Ground-water, surface-water, and water-chemistry
2007 Truini, Margot, and Macy, J.P. data, Black Mesa area, northeastern Arizo- Open-File Report 2007–1041
na—2005–06
Ground-water, surface-water, and water-chemistry
2008 Truini, Margot, and Macy, J.P. data, Black Mesa area, northeastern Arizo- Open-File Report 2008–1324
na—2006–07
Groundwater, surface-water, and water-chemistry data,
2009 Macy, J.P. Open-File Report 2009–1148
Black Mesa area, northeastern Arizona—2007–2008
Groundwater, surface-water, and water-chemistry data,
2010 Macy, J.P. Open-File Report 2010–1038
Black Mesa area, northeastern Arizona—2008–2009
Groundwater, surface-water, and water-chemistry data,
2011 Macy, J.P., and Brown, C.R. Open-File Report 2011-1198
Black Mesa area, northeastern Arizona—2009–2010
Macy, J.P., Brown, C.R., and Groundwater, surface-water, and water-chemistry data,
2012 Open-File Report 2012-1102
Anderson, J.R. Black Mesa area, northeastern Arizona—2010–2011
Groundwater, surface-water, and water-chemistry data,
2014 Macy, J.P., and Unema, J.A. Open-File Report 2013-1304
Black Mesa area, northeastern Arizona—2011–2012
Groundwater, surface-water, and water-chemistry data,
2015 Macy, J.P. and Truini, Margot Open-File Report 2015-1221
Black Mesa area, northeastern Arizona—2012–2013
Groundwater, surface-water, and water-chemistry data,
2017 Macy, J.P., and Mason, J.P. Open-File Report 2017-1127
Black Mesa area, northeastern Arizona—2013–2015
Groundwater, surface-water, and water-chemistry data,
2018 Mason, J.P., and Macy, J.P. Open-File Report 2018-1193
Black Mesa area, northeastern Arizona—2015–2016Description of Study Area 9
program, a large data-collection effort in the 1950s resulted in below sea level now rise over 8,000 feet above sea level. As
a compilation of well and spring data for the Navajo and Hopi a result of this uplift, the region has gone from a depositional
Indian Reservations (Davis and others, 1963). cycle to an erosional cycle. Much of the erosion responsible for
Many interpretive studies have investigated the hydrology present day topography likely occurred in the past 10 million
of the Black Mesa area. Cooley and others (1969) made the years (Lazear and others, 2013). Since uplift occurred, Black
first comprehensive evaluation of the regional hydrogeology Mesa has been dissected by streams, resulting in the formation
of the Black Mesa area. Eychaner (1983) developed a two- of numerous smaller mesas such as the Hopi Mesas.
dimensional numerical model of groundwater flow in the N The geologic units that comprise the N aquifer occur at or
aquifer. Brown and Eychaner (1988) recalibrated Eychaner’s near the land surface in a large extent around the periphery of
model by using a finer grid and by using revised estimates Black Mesa. In these areas the aquifer is generally unconfined.
of selected aquifer characteristics. GeoTrans, Inc. (1987) West of Kayenta, exposed N aquifer units form Skeleton Mesa
also developed a two-dimensional numerical model of the N and the Shonto Plateau. At the southeast edges of these features,
aquifer in the 1980s. In the late 1990s, HSIGeoTrans, Inc. and the aquifer units are folded by the Organ Rock monocline
Waterstone Environmental Hydrology and Engineering (1999) (fig. 3) and plunge steeply to the southeast below the younger
developed a three-dimensional numerical model of the N Cretaceous rocks of Black Mesa forming Long House Valley.
aquifer and the overlying D aquifer. The N aquifer units continue to the southeast under Black Mesa
Kister and Hatchett (1963) made the first comprehensive eventually reappearing south of the Hopi Mesas. The aquifer
evaluation of the chemistry of water collected from wells units pinch out not far from where they reappear. In general, the
and springs in the Black Mesa area. HSIGeoTrans, Inc. confined portion of the N aquifer occurs where the aquifer units
(1993) evaluated the major-ion and isotopic chemistry of are deeply buried beneath Black Mesa.
the D and N aquifers. Lopes and Hoffmann (1997) analyzed The paths of stream channels also are influenced by
groundwater ages, recharge, and hydraulic conductivity of physiography. Geologic structural folds, joint patterns, rock
the N aquifer by using geochemical techniques. Zhu and type, and topography all affect the flow of surface water in
others (1998) estimated groundwater recharge in the Black the study area. Major streams of the study area are shown
Mesa area by using isotopic data and flow estimates from the in figure 1. The surface topography of Black Mesa slopes
N-aquifer model developed by GeoTrans, Inc. (1987). Zhu downhill from northeast to southwest. Likewise, the major
(2000) estimated recharge using advective transport modeling streams that drain Black Mesa flow from northeast to
and the same isotopic data from the GeoTrans model. Truini southwest toward the Little Colorado River.
and Longsworth (2003) described the hydrogeology of the
D aquifer and the movement and ages of groundwater in the Climate
Black Mesa area by using data from geochemical and isotopic
analyses. Truini and Macy (2005) looked at possible leakage The climate in most of the Black Mesa area is
through the confining unit between the D aquifer and the N broadly classified by Hendricks (1985) as steppe, which is
aquifer as part of an investigation of the Carmel Formation. characterized by limited amounts of precipitation. Much of the
precipitation in steppe regions evaporate before it can infiltrate
to groundwater. As a result, the vegetation cover consists
Description of Study Area
The availability and chemistry of water resources within
the Black Mesa area are directly related to physiography,
climate, and geology. Physiography affects the movement of
both surface water and groundwater in the area, and climate
affects the water budget. The complex geologic history of
the area has resulted in the accumulation of abundant coal
resources and influences the movement and chemistry of
surface water and groundwater.
Physiography
The Black Mesa area is in the Colorado Plateau Physio-
graphic Province of the Rocky Mountain Region (Raisz, 1972).
The dominant physiographic feature in the study area is Black
Mesa itself, but numerous smaller features play an important Figure 3. Aerial photograph of Organ Rock monocline and
role in the movement of surface water and groundwater (fig. 1). folding strata of Skeleton Mesa near Kayenta, Arizona. The Navajo
Black Mesa is the remnant of a large sedimentary basin that has Sandstone is truncated in this part of the monocline, forming the
undergone substantial tectonic deformation and uplift during flatirons along the lower part of the monocline. Photograph by
the past 70 million years. Parts of Black Mesa which were once Jodi Norris.10 Groundwater, Surface-Water, and Water-Chemistry Data, Black Mesa Area, Northeastern Arizona—2016–2018
mostly of mesquite, pinyon-juniper, and various grasses precipitation data from traditional weather stations and high-
(Hendricks, 1985). A small area around Tuba City is classified altitude meteorological sites (Daly and others, 1994). Based
by Hendricks (1985) as desert, signifying even less annual on 30-year averages from 1981–2010, annual precipitation in
rainfall and a vegetative cover consisting mostly of creosote the Black Mesa area ranges from less than 6 inches (in) in the
bush, cacti, and sagebrush. lower elevation regions around the mesa to more than 16 in
Mean annual precipitation for the Black Mesa area was at the highest elevations on the mesa (fig. 4; PRISM Climate
estimated using spatial regression methods that incorporated Group, 2018).
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Base from U.S. Geological Survey digital data, 2010 0 25 MILES Climate data from PRISM Climate Group, 2018;
Lambert Conformal Conic projection 30-year normal annual data, 1981-2010,
Standard parallels 29°30’ N. and 45°30’ N. 0 25 KILOMETERS 4 km resolution; July 2012
central meridian -111°30’ W.
EXPLANATION Map area
Annual precipitation, in inches
4.1 to 6.0
6.1 to 8.0 Black Mesa
8.1 to 10.0
A R I Z O N A
10.1 to 12.0
12.1 to 14.0
14.1 to 16.0
Figure 4. Map showing mean
16.1 to 18.0
annual precipitation, 1981-2010,
Boundary of Black Mesa Black Mesa area, Arizona.Description of Study Area 11
According to Sellers and Hill (1974), about 60 percent demise of the Laramide flat slab, [or] late Tertiary time coeval
of average annual precipitation in northeastern Arizona falls with regional extensional tectonism in adjacent provinces.”
between the months of May and October (primarily in July
and August). They report that, on average, the plateaus and Geologic Units Below the N Aquifer
mesas of northeastern Arizona are the driest part of the state
during the colder half of the year and rarely receive heavy The geologic units below the N aquifer system are Trias-
winter precipitation. Using more recent precipitation data, sic and older in age (fig. 2) and generally are not suitable as a
an analysis of 30-year normal precipitation for the period water supply in the Black Mesa area and will not be discussed
1981–2010 (PRISM Climate Group, 2018) in the Black Mesa in detail. The Permian Coconino Sandstone and Kaibab Lime-
area show that about 55 percent of precipitation occurred stone (fig. 2) can produce adequate quantities of water in the
from May–October. An important factor when thinking about Black Mesa area, but they are deeply buried and likely have
recharge to the N aquifer is that much of the groundwater total-dissolved solids concentrations above what can be used
contained in the N aquifer was recharged during the late without treatment.
Pleistocene when the temperature was cooler and precipitation
amounts were higher (Zhu and Kipfer, 2010). Geologic Units of the N Aquifer
The geologic units that make up the N aquifer are mem-
Geology
bers of the Glen Canyon Group and include the Moenave
The stratigraphic section (fig. 2) used in the current and Formation, Wingate Sandstone, Kayenta Formation, and
previous Black Mesa monitoring reports was modified from Navajo Sandstone (fig. 2). The group is named after Glen
Harshbarger and others (1966). The original stratigraphic Canyon of the Colorado River in southeastern Utah where
section showed the Wingate Sandstone occurring between the these units are typically exposed (Harshbarger and others,
Chinle Formation and the Kayenta Formation and did not have 1957). The Glen Canyon Group was originally thought to be
the Moenave Formation present. More recently, Billingsley Late Triassic to Early Jurassic in age (Harshbarger and others,
and others (2012, 2013) concluded that sandstones in the Black 1957), but more recent paleontological and stratigraphic
Mesa area formerly mapped in outcrop as Wingate Sandstone discoveries strongly suggest the group is largely Early Jurassic
are in fact part of the Moenave Formation. It is unclear if the in age (Peterson and Pipiringos, 1979). According to Blakey
Wingate Sandstone could be present in the subsurface under and Ranney (2008), when the Glen Canyon group was
parts of the Black Mesa area. Since the two geologic units deposited, the Black Mesa Basin was slightly above sea level
are considered coeval, the Moenave Formation is shown as and the climate was windy and dry. This led to widespread
present and possibly intertongued with the Wingate Sandstone deposition of eolian and fluvial deposits (Blakey and Ranney,
in figure 2. Harshbarger and others (1966) considered the eolian 2008) that now compose the sandstone units of the N aquifer.
facies of the Wingate Sandstone to be a water-bearing unit of Where the N aquifer is confined it is capped by the
the N aquifer. It is unclear if any of the sandstones now mapped Carmel Formation (fig. 2), which is considered part of the
as Moenave Formation could be water bearing. San Rafael Group; the Carmel Formation is discussed in
Rocks of Triassic age and older are not discussed in this section since it both confines the aquifer in places and
detail in this report because they are not significant sources hydraulically separates the N aquifer from the overlying D
of groundwater in the Black Mesa area. Instead, this section aquifer, where the D aquifer is present.
focusses on Jurassic and younger rocks that are part of hydro-
logic systems utilized in the Black Mesa area. Moenave Formation
The Black Mesa area is the remnant of a large sedimen- The Moenave Formation (fig. 2) contains several mem-
tary basin that has been uplifted and dissected by streams since bers with the most prominent one in the Black Mesa area
its original formation. When the sedimentary rock units (fig. 2) being the Dinosaur Canyon Member. Blakey and Ranney
in the Black Mesa area were deposited the region had a much (2008) described the Moenave Formation as being deposited
lower surface elevation nearer to, and sometimes below, sea by northwest flowing streams, concurrently the Wingate
level. As the thick sequence of sedimentary rock units was Sandstone was being deposited to the northeast. Billingsley
being deposited, the basin was slowly subsiding, allowing and others (2012) described the lithology of the formation
more sediments from nearby highlands to be deposited. The as reddish-brown, thin, flat, and crossbedded, fine to coarse-
entire Colorado Plateau including Black Mesa was tectonically grained fluvial siltstone and silty sandstone.
uplifted a mile above sea level during the Tertiary by processes The Moenave Formation forms distinctive orange-red
that are still not fully understood. According to Flowers (2010), cliffs along the southwest edge of the Moenkopi Plateau and
Colorado Plateau “elevation gain could have occurred in early west of Oraibi Wash on Garces Mesas (figs. 1 and 5). The
Tertiary time associated with [the] Sevier-Laramide contrac- Moenave Formation is not known to yield economic quantities
tion, middle-Tertiary time synchronous with the proposed of water in the Black Mesa area.You can also read
